Did you order with the thermal battery???
(Inquiring minds want to know ...)
= )

Permaculture is a gestalt ... a study of the whole. Not just how to produce more and better food, but how human life on the planet affects and is affected by the surrounding environment.
Bill Kearns http://columbiabasinpermaculture.com

I have seen a variety of solar stoves, and I know that they can be effective, and I know that they can be effective at a small fraction of this price. But this one looks fast, powerful, self-contained, and easy-to-use-bordering-on-fool-proof. It isn't just a solar cooker; its a plug-and-play solar cooker. That will appeal to a lot of folks out there. I for one say "hell yeah!" Looks totally worth the price. I'm getting one, and I predict these people are going to make some bank and do a lot of good in the process.

Based on the cooking charts available on the company's website (and those are for the portable Sport model; I am guessing the full grill available through this kickstarter is even more powerful), this thing cooks fast. Fast enough that it is a viable replacement for your gas or electric oven. Other simpler and cheaper solar stoves I have seen are more like a replacement for your slow cooker.

One thought, though: they describe it as a "grill" and clearly are marketing it as a competitor to charcoal or gas grills, but the way it cooks seems more to me like an oven than a grill. It bakes food, looks like; rather than grilling it. Really two distinct cooking techniques.

That looks really good. It seems well designed and takes care of the problems I had when using my home made unit such as wind and pointing (though pointing would still help). It also seems like it would be much more efficient. I do wonder what phase change material they use... or if I can't find that out, at least what temperature it changes phase at and how long a fully charged phasechange "battery" lasts... both with an empty oven and with a load. (edit: it says cooks to 300 to 400F... which still doesn't tell me what the phase change temp is. But it is not tin)

Matthew Nistico

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Posts: 319

Location: Clemson, SC ("new" Zone 8a)

21

posted 3 years ago

@Len - Read through the KickStarter and gosunstove.com materials more closely. They say it is an organic wax, though they don't name the actual compound, and that its melting point is a little over 300 degrees.

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Len Ovens

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Posts: 1471

Location: Vancouver Island

31

posted 3 years ago

Matthew Nistico wrote:@Len - Read through the KickStarter and gosunstove.com materials more closely. They say it is an organic wax, though they don't name the actual compound, and that its melting point is a little over 300 degrees.

Sounds good. I was hoping it was not toxic (sulfer is in around that range somewhere). I wonder how many cycles it is good for. It would break down through cycles and the phase change temperature will probably drop over time (I would guess).

Matthew Nistico

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Posts: 319

Location: Clemson, SC ("new" Zone 8a)

21

posted 3 years ago

Len Ovens wrote:

Matthew Nistico wrote:@Len - Read through the KickStarter and gosunstove.com materials more closely. They say it is an organic wax, though they don't name the actual compound, and that its melting point is a little over 300 degrees.

Sounds good. I was hoping it was not toxic (sulfer is in around that range somewhere). I wonder how many cycles it is good for. It would break down through cycles and the phase change temperature will probably drop over time (I would guess).

At the risk of repeating myself: read through the KickStarter and gosunstove.com materials more closely. At the bottom of the main KickStarter page there is a FAQ all about the thermal battery. Here, I will just copy the complete text:

Thermal Battery: How Does it Work?
The simple four pound (1.8kg) module is placed inside the GoSun Grill to preheat for a couple hours before cooking. Using the latent-heat capacity of our proprietary PCM (short for Phase Change Material) encapsulated within an aluminum extrusion, the Thermal Battery is able to store much more energy than a material with only sensible heat (such as concrete or sand). Through the process of melting the PCM at roughly 310°F or 155°C, the Sun’s energy is stored for use later in the day. Capable of reaching temperatures over 400°F or 205°C, this heat is fully insulated while left inside the evacuated tube chamber. When the Cooking Pans are placed on top of the Thermal Battery, the reverse of the melting cycle begins where the PCM begins to transfer its stored heat into the cool, uncooked food. Conduction between the hot Thermal Battery and the food is very strong since they are virtually in contact with one another, separated by two layers of metal. The food cooks quickly as heat rises from the Battery and the PCM slowly cools (actually changes phases, aka freezes) back to its solid state.

Thermal Battery: Is it Safe?
This is not an electric battery. It is not acid-based and it is a not corrosive. It is a safe, non-toxic organic wax that is encased in an aluminum vessel. When used to cook food inside the GoSun Grill, the Thermal Battery Module is located underneath the Cooking Pans. There is no risk for cross contamination since the Thermal Battery is hermetically sealed. Users will need to exercise cautioun when removing the Tray, as the Thermal Battery and the Cooking Pans will be hot.

Thermal Battery: How do you use the Thermal Battery?
Please also refer to the video on the Kickstarter page. The Thermal Battery is first placed inside the GoSun Grill, on top of the Tray, about two hours before preparing a meal to allow ample time for it to heat up. Once preheated, the Tray is carefully opened so the Cooking Pans can be placed on top of the Battery. The Tray is then pushed back into the tube so the meal can cook inside the highly insulated chamber.

Thermal Battery: Will it last?
The PCM (Phase Change Material) is capable of a high number of completely reversible freeze/melt cycles so it is designed to last for years. After extensive testing, we have found no noticeable degradation in the non-flammable, non-toxic PCM.

Thermal Battery: How long does it take?
The Thermal Battery takes roughly two hours to heat up to maximum temperature in full sun. Once preheated, cooking times are significantly reduced since the food is in direct contact with the heat when placed on top of the Battery.

Thermal Battery: How much heat is available?
The Thermal Battery has been designed with enough capacity to autonomously cook a meal for eight people. For example, this could be four pounds of chicken or four loaves of bread. [for actual stats, see below]

Fulfillment: Can I buy the accessories separately a later date?
Yes, www.gosunstove.com will carry the full line of options and accessories related to the GoSun Grill and our other product lines. However, we encourage customers to purchase through Kickstarter since these are our best prices.

The battery was inspired by our work in Guatemala during its extensive rainy season. Our pilot study’s participants used the stoves daily, but needed a solution that could cook in the afternoon rain. What started as a simple sand filled battery, became the subject of a year long exploration to find a medium that could absorb large amounts of heat and emit that heat at an even temperature for optimal cooking.

The Thermal Battery has a few key benefits that are not so obvious until you try it. Firstly, the battery helps instill confidence in your solar cooking ventures. With a charged battery you can cook in confidence that no matter the weather, your food will still finish. The battery is also a more intelligent way to utilize the potential of the GoSun cooking technology, capturing every last drop of sunshine and converting that into useable heat down the road.

Sunlight just doesn't have the flavor of mesquite wood smoke. I'm not seeing several hundred dollars worth of benefit here over burning trash wood (everybody with land around here has mesquite to get rid of) in a $40 Weber.

As I read the thread some red flags were raised in my mind since I have conducted many test like these….I don’t have the time to research the site but here are some concerns based on thread content.

Thermal Battery: Is it Safe?

“Thermal Battery is hermetically sealed”

Definition: “A hermetic seal has the quality of being airtight. In common usage, the term often implies being impervious to gases. When used technically, it is stated in conjunction with a specific test method and conditions of usage."

"Using the latent-heat capacity of our proprietary PCM (short for Phase Change Material) encapsulated within an aluminum extrusion, the Thermal Battery is able to store much more energy than a material with only sensible heat (such as concrete or sand). Through the process of melting the PCM at roughly 310°F or 155°C,”

Just about every time I have researched “proprietary” materials I find issues or nothing new. I get really concerned about this term in building products, and VERY concerned when it is in “direct contact” with food (separated by “aluminum”). It is not the “PCM” itself, it is the PCMs reaction with the aluminum grade at different PCs and a rate of emittance to a foods of different types. The reaction will occur at the interface of the materials (PCM/AL) first, not the “safe” cooking surface unless there is a food that reacts with the materials(s) and phases. So we are not looking for a single material thermal or toxicity property and that is what alot of manufactures, especially claiming naturally safe do, rather we are looking for states of the combined “material(s) or assembly or chemical reactions and interactions” properties. Inert, stable, materials would be others and proof of it. So what I would hope to see in the product testing I cook with and what I trust going in my body is first and foremost the materials completely disclosed. One might say that it is understandable not to for competitive market reasons. That is why we have patents and why all materials we cook with should be identified. The volumetric dimensional properties are the other side of the equation here, I am not asking for them, so the design is still unknown. I would expect at a minimum to disclose the grade of aluminum (ie: 6 or 7 series aluminum takes high heat cyclic fatigue well but, it is chem treated to prevent corrosion especially when used outdoors, well I would hope so corrosion does not end up in our foods. So we should expect to see a final test report of emittance (gas, particle type and size, number per million) in a test made available to the public. Not just a statement saying it is “hermetically sealed”, that is IF the company has put the money into the appropriate testing and has nothing to hide.

Thermal Battery: Will it last?
“The PCM (Phase Change Material) is capable of a high number of completely reversible freeze/melt cycles so it is designed to last for years. After extensive testing, we have found no noticeable degradation in the non-flammable, non-toxic PCM. “

The statement “last for years” tells me they do not know. When I conduct fatigue life cycle test we take the product to what is called “ultimate failure”. We set up a bench test to cycle the product until it fails noting the number of cycles. That number is noted in a final test report. You will this same lack of data in A LOT of mainstream building products, since it cost money to simulate the environment that the product will be used in a test box and have test apparatus to cycle it 27-7 to failure taking test reading along the way.
The test design should also look at toxic emittance over the cycle life and the test report should disclose those values IF it was conducted. If you have conducted the appropriate toxicity test the fatigue life test does not cost much more since the test fixtures and instrumentation is already there, and visa vera, which makes me believe they did not do the comprehensive co-testing of toxicity either.

If anyone can find this third party testing from a qualified lab governed by appropriate test standards please do post them. Otherwise, do not believe everything a manufacture says about their product. Another red flag is when you see big fancy words to try and get the public to accept them over well-funded quality assurance testing. Typically, a third party is also involved in witnessing the test is being conducted to an approved standard. I have been a part of this and many manufactures over the years.

The product may be perfectly fine but, just wanted to help readers quantify and qualify the statements being made. I'm sure if you look there is a lot of cookware that fails to do the testing as this one is no different like they claim. I personally do not trust my heath to unknowns, especially some new "proprietary PCM".

As I read the thread some red flags were raised in my mind since I have conducted many test like these….I don’t have the time to research the site but here are some concerns based on thread content.

Thermal Battery: Is it Safe?

“Thermal Battery is hermetically sealed”

Definition: “A hermetic seal has the quality of being airtight. In common usage, the term often implies being impervious to gases. When used technically, it is stated in conjunction with a specific test method and conditions of usage."

"Using the latent-heat capacity of our proprietary PCM (short for Phase Change Material) encapsulated within an aluminum extrusion, the Thermal Battery is able to store much more energy than a material with only sensible heat (such as concrete or sand). Through the process of melting the PCM at roughly 310°F or 155°C,”

Just about every time I have researched “proprietary” materials I find issues or nothing new. I get really concerned about this term in building products, and VERY concerned when it is in “direct contact” with food (separated by “aluminum”). It is not

I get the idea they heat cycled enough times to hit two years at once day... maybe. I also expect the heat cycle they tested was just hot enough to fully phase change and not to the 400F or more it may see on a really sunny day. I wonder if the cycle testing done did test also how the PC material degrades over time. Sealed or not I do not see how CH (Carbon) based PC material will not change it's composition through heat cycles. A changing composition will change the PC point as well as spreading it out. If the PC point gets low enough, it is no longer helping cook and one may as well use a cast iron brick. Yes actual test results would be nice.

I do not think any one is expected to cook food directly on the "battery" but rather in a pan on top. but the point of gasious/particulate emisions is valid.

Another thing for the user to be aware of, is that cooking in the dark using the battery will be different than cooking in the sun. The page does mention the "good" conduction from battry to pan to food by contact... this may not be the good thing it seems, 310F is hot enough to burn things on the bottom.

I do think this is still a good product. The solar part anyway, the battery part we will have to see. (I wonder what the boiling point is, don't throw this in the fire to jump start it)

Matthew Nistico

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Posts: 319

Location: Clemson, SC ("new" Zone 8a)

21

posted 3 years ago

Len Ovens wrote:I do not think any one is expected to cook food directly on the "battery" but rather in a pan on top. but the point of gasious/particulate emisions is valid.

Thank you for pointing that out.

Len Ovens wrote:Another thing for the user to be aware of, is that cooking in the dark using the battery will be different than cooking in the sun. The page does mention the "good" conduction from battry to pan to food by contact... this may not be the good thing it seems, 310F is hot enough to burn things on the bottom.

Yes, I was thinking the same thing. There is a difference between cooking via ambient heat and via conductive heat from one source (i.e. from the bottom). That difference could translate to burnt food, especially if the material of the pan is thin.

Still, I am guessing that the pros outweigh the cons and am still looking forward to receiving my cooker with battery.

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Len Ovens

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Location: Vancouver Island

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posted 3 years ago

Matthew Nistico wrote: Still, I am guessing that the pros outweigh the cons and am still looking forward to receiving my cooker with battery.

Ya, if I had the money to throw at it, I would go for it too.

What I would find interesting is to use the "battery" in other ways than intended Perhaps to get two and build a more conventional style oven box, but still super insulated. Or maybe in the winter to use as a space heater for a small room that is unable to gather heat from the sun.

I would prefer to work with Tin or Bisuth as phase change material, both hotter and denser and more stable too.... but harder to ensure the melt phase change was affected with a solar source. Tin has to sit at 450F and bismuth at 520F. Easy to do with a wood fire...

Usually you have to get the phase change material considerably hotter than melt point to start to degrade it, but 450-500 may easily do it.

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Matthew Nistico

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Posts: 319

Location: Clemson, SC ("new" Zone 8a)

21

posted 3 years ago

Len Ovens wrote:What I would find interesting is to use the "battery" in other ways than intended ...Or maybe in the winter to use as a space heater for a small room that is unable to gather heat from the sun.

Heck yeah! I have already thought about that possibility, as the passive solar home I'm building has such rooms and no central heating system. At first, when relying on a wood stove (in the main room) for heat, I can always sit a metal bucket full of rocks atop the stove for bedtime transport into the back bedroom to boost nighttime temps. But in later years, when I've replaced the wood stove with a planned rocket mass heater and am only firing the heater every other day, or even less often, and for short periods not necessarily in the evenings... enter solar oven that can sit out in the afternoon and soak up heat and store it inside a vacuum tube for nighttime transfer to the floor of cold bedroom : )

Matthew Nistico wrote: At first, when relying on a wood stove (in the main room) for heat, I can always sit a metal bucket full of rocks atop the stove for bedtime transport into the back bedroom to boost nighttime temps.

This is rather off topic, but I just wanted to say: Thank you so much for this idea! We have a woodstove, and I've been trying to think of affordable ways to add more mass to it. We already have soapstone on top of the stove that was gifted to us, but I wanted to add more mass. Our rocks don't stack here, and stacking soapstone next to it would be expensive. But, a nice metal bucket of rocks is cheap and easy. Thank you!

Perhaps they are using paraffin wax as a PCM. It has a melting point of around 100 F at room temperature where it begins to melt as determined in a lab under constant pressure. The pressure inside the chamber raises the melting to point to ~ 300F or they can dilute it with soluble materials like esters or benzene to take down its density. It’s a petroleum based product made of coal or oil shale that in bead form has also made its way into plasters, drywall, and other building materials. It is a vapor barrier that would not allow wall/roofs to breathe and dry out so I do not recommend it, however, it has a high thermal storage capacity. It has high heat fusion rates that would act to transfer toxins readily unless they are burnt off, even so they can still outgas to food.

I'm not aware of another wax with such thermal or PCM properties unless they have a patent on their "Proprietary PCM". If they do I would expect to see it replace paraffin wax and I am sure they will make a fortune selling the raw materials to several markets. Red flags also raise in my mind when the advertising to get you buy one involves support to third world poverty stricken countries. I'd like to see what percentage of profits are going to them. I would think a better market approach would be to fully test and disclose...but that's just me.

Nicole Alderman wrote:This is rather off topic, but I just wanted to say: Thank you so much for this idea! We have a woodstove, and I've been trying to think of affordable ways to add more mass to it. We already have soapstone on top of the stove that was gifted to us, but I wanted to add more mass. Our rocks don't stack here, and stacking soapstone next to it would be expensive. But, a nice metal bucket of rocks is cheap and easy. Thank you!

You're welcome. It is an old cold weather camping technique someone told me once. Heat rocks in coals of evening cookfire, then use bucket to transfer into tent for the night. You just have to be very careful where you place the bucket, so it doesn't melt tent, or sleeping bag, or you! : )

Blazing trails in disabled homesteading

Matthew Nistico

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Posts: 319

Location: Clemson, SC ("new" Zone 8a)

21

posted 3 years ago

1

Terry Ruth wrote:Red flags also raise in my mind when the advertising to get you buy one involves support to third world poverty stricken countries. I'd like to see what percentage of profits are going to them.

Although you raise an excellent point about emotionally manipulative marketing in general, I think you may have misunderstood GoSun's marketing in this case.

Now, don't take this as definitive in any way, because I don't wish to speak on these people's behalf, but my take from the info in the kickstarter video was quite different. I don't think they are promising to make charitable donations to Guatemalan poor if you buy their stoves. Rather, I understood them to be saying that they developed their stoves with the idea in mind to market this technology - or I am guessing a less expensive derivative of this technology, since their site claims the ability to manufacture and deliver one stove to an impoverished country for $100 - to Guatemalan poor as a better alternative to the open wood fires currently in use to cook food. Certainly this is a huge problem throughout the developing world, leading to 1) continued poverty, based on the excessive time and/or money consumed just gathering fuel; 2) resource depletion through unnecessary deforestation; and most of all 3) serious health problems, based on a lifetime spent breathing smoke from open fires. Recall that these are the same three problems that originally inspired invention of rocket stoves.

I agree, there is precious little hard info offered on their website. Perhaps a deeper online search could turn up more. But they do say (at http://gosunstove.com/pages/about-us) that "GoSun’s business model has two distinct initiatives: GoSun Stove and GoSun Global, with different strategies, product offerings and markets that share the same basic technology. GoSun Global is a social enterprise leveraging business and impact investing as a mechanism to perform good in the developing world." And about the latter, they offer a little more info at http://gosunstove.com/pages/empowerment, including a summary of the results of their pilot study in Central America.

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Terry Ruth

Posts: 698

26

posted 3 years ago

Matthew Nistico wrote:

Terry Ruth wrote:Red flags also raise in my mind when the advertising to get you buy one involves support to third world poverty stricken countries. I'd like to see what percentage of profits are going to them.

Although you raise an excellent point about emotionally manipulative marketing in general, I think you may have misunderstood GoSun's marketing in this case.

Now, don't take this as definitive in any way, because I don't wish to speak on these people's behalf, but my take from the info in the kickstarter video was quite different. I don't think they are promising to make charitable donations to Guatemalan poor if you buy their stoves. Rather, I understood them to be saying that they developed their stoves with the idea in mind to market this technology - or I am guessing a less expensive derivative of this technology, since their site claims the ability to manufacture and deliver one stove to an impoverished country for $100 - to Guatemalan poor as a better alternative to the open wood fires currently in use to cook food. Certainly this is a huge problem throughout the developing world, leading to 1) continued poverty, based on the excessive time and/or money consumed just gathering fuel; 2) resource depletion through unnecessary deforestation; and most of all 3) serious health problems, based on a lifetime spent breathing smoke from open fires. Recall that these are the same three problems that originally inspired invention of rocket stoves.

I agree, there is precious little hard info offered on their website. Perhaps a deeper online search could turn up more. But they do say (at http://gosunstove.com/pages/about-us) that "GoSun’s business model has two distinct initiatives: GoSun Stove and GoSun Global, with different strategies, product offerings and markets that share the same basic technology. GoSun Global is a social enterprise leveraging business and impact investing as a mechanism to perform good in the developing world." And about the latter, they offer a little more info at http://gosunstove.com/pages/empowerment, including a summary of the results of their pilot study in Central America.

At the risk of repeating myself read my post more closely

The burden of proof that the unit is not doing more harm than good is on the manufacturer. Again, that requires the proper testing and/or disclosure of materials (eg: petro based waxes in contact with chem treated AL) , especially if you are selling the product at a discount to poverty stricken countries. Lets not put the cart before the horse. I do like the creative sales marketing and legal protection strategies, create local and global entities. I been around these manufactures for decades and still am. I'm always interested in what they will try next. This one may be perfectly legit, but until I see proof I don't buy it. I may buy one just to get to that PCM and go get it lab tested.

Well now, that's quite a discussion on the battery. Thanks, savvy people!

I bought the "grill" which to me is a cooker, and considered the battery, then bought without. Now, I am watching the progress towards the stretch goal which gives me two extra cooking pans, and was thinking I might get the battery if the total got close. WE are 8 days out and need another 38 thousand dollars to get to the next stretch goal. (They only have 2, one a device that helps orient to the sun for optimum heat capture, and the next, 50 thousand more gives the two extra cooking pans).

I think it will be a great thing to have. Think I am likely to use it more than my gas oven, probably learn to cook rice and bread etc etc in it, maybe even set it up for morning tea to start itself when the sun rises...

But, I am glad to read the discussion about proprietary materials and interactions with other materials at high temperatures, and degradation of materials at high temperatures, the ethics of appealing to the emotions of affluent populations by bringing in the poor people in other lands, and what they plan to do for them.

I still think I will love my solar cooker, but it's good to be aware of the ways I may have been manipulated, and the ways the selling and marketing entity could be more honest, forthcoming and ethical.

We're considering getting one of these, so we can cook outside on our tiny village homestead as much as possible this summer, but it's a fair chunk o' change. We'd love to hear back from those of you who've (finally!) received yours. How are they performing? Was the PCM mystery ever solved?

Thanks!

Matthew Nistico

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Posts: 319

Location: Clemson, SC ("new" Zone 8a)

21

posted 1 year ago

2

I received mine just very recently. I will update on this thread when I've gotten some repeat experiences cooking with it.

They ran into problems with the PCM battery and cut it out of the equation early on in the manufacturing process. Kickstarter backers got their money back for the battery option. Now they offer an optional electric element for night-time cooking. I didn't opt for that.

Blazing trails in disabled homesteading

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